Mineral veins on Mars. Curiosity rover image of two-tone mineral veins on the surface of Mars, at an area called Garden City on lower Mount Sharp. These veins jut up to heights of up to around 6cm above the surrounding rock and reach depths of around 4cm. Mineral veins such as these form where fluids move through fractured rocks, depositing minerals in the fractures and affecting chemistry of the surrounding rock. In this case, the veins have been more resistant to erosion than the surrounding host rock. Imaged by Curiosity's Mast Camera (MastCam), on 18th March 2015.